**Let the original salary = Rs.100 **

**Then, **

After increment of 25% = 100 (1 + 25/100)

= 100 (125/100)

= Rs.125

**Now, **

To restore the original salary,

Let the new salary decreased by Z%

∴ 125(1 – Z/100) = 100

⇒ (1 – Z/100) = 100/125

⇒ (1 – Z/100) = 4/5

⇒ Z/100 = 1/5 [1 – 4/5 = 1/5]

⇒ Z = 100/5

⇒ Z = 20%